Oxygen reactions in high-pressure nitrogen gas studied with optical emission spectroscopy.

A study of some oxygen reactions in irradiated high-pressure (0.34-3.3MPa) nitrogen gas is presented. Nitrogen gas containing < or =1ppm H(2)O and O(2) was irradiated in a closed target chamber with 4.3MeV protons. Optical emission spectra of the NO-gamma (A(2)Sigma(+)-X(2)Pi), the NO-beta (B(2)Pi-X(2)Pi) and the O ((1)S-(1)D) transitions were recorded as a function of irradiation time at four different nitrogen-gas pressures. The results show a coupling between the NO-gamma build-up half time and the NO-beta decay and the O ((1)S-(1)D) decay half times as a function of irradiation time. The binding of free atomic oxygen in reactions forming NO has implications for the balance of [(11)C]CO(2) versus [(11)C]CO production.